…a calling requires certain preconditions. It requires more than desires; it requires talent. Not everyone can be, simply by desiring it, an opera singer, or professional athlete, or leader of a large enterprise. For a calling to be right, it must fit our abilities. Another precondition is love — not just love of the final product but, as the essayist Logan Pearsall Smith once put it, “The test of a vocation is love of drudgery it involves.” Long hours, frustrations, small steps forward, struggles: unless these too are welcomed with a certain joy, the claim to being called has a hollow ring.
—Working: Its Meaning and Its Limits, ed. Gilbert C. Meilaender (Notre Dame: Notre Dame University Press, 2000), pp.124-125, emphasis mine